How does the HTML formatter handle nested tags and indentation?

The formatter uses Prettier's HTML printer, which walks the full parse tree and re-indents every nested element with a consistent two-space indent by default. Each child element is placed on its own line, and deeply nested structures are indented proportionally, making the hierarchy immediately readable.

Are self-closing tags preserved when formatting HTML?

Yes. Prettier distinguishes between void elements like , , and — which are always rendered as self-closing — and regular elements. Non-void elements with no children are kept as open/close pairs, so your semantics stay intact and browsers parse the output correctly.

Can I change the indent size or tab width?

The current tool runs with Prettier's default tab width of 2 spaces, which aligns with the most widely adopted HTML style guides. Future updates plan to expose a tab-width selector so you can choose 2 or 4 spaces to match your project's existing conventions.

How does Prettier format long attribute lists on HTML elements?

When an element's opening tag exceeds the print-width threshold (80 characters by default), Prettier breaks each attribute onto its own indented line and places the closing > on a new line. This keeps long attribute lists scannable without horizontal scrolling.

Can I paste minified HTML and get it fully formatted?

Absolutely. Minified HTML — including single-line documents with collapsed whitespace — is fully supported. Prettier rebuilds the AST from the minified source and outputs properly indented, readable HTML regardless of how compressed the input is.

Which version of Prettier is used by the HTML formatter?

The tool bundles Prettier 3.x (MIT-licensed), which ships with an improved HTML parser that handles template literals and whitespace sensitivity more accurately than version 2. The exact version is pinned in the project's package.json to ensure reproducible formatting output.

Does the formatter support HTML flavors like Vue templates or Jinja?

The formatter targets standard HTML5. Prettier does include partial support for Vue single-file component templates when the parser is set to "vue", but the current tool focuses on plain HTML. JSX, Jinja, and Nunjucks are not supported in this tool's current configuration.

How fast is the in-browser HTML formatter for large files?

Prettier runs entirely in your browser via WebAssembly, so formatting is typically instantaneous for files under 500 KB. Even large HTML documents with thousands of lines complete in under one second on a modern device. No network round-trip means zero latency from server calls.

HTML Formatter

Format and beautify HTML code instantly in your browser with Prettier (the industry-standard formatter, MIT-licensed). No uploads, no sign-up, works offline.

100% Private — Runs entirely in browserInstant calculation & resultFree, no sign-up

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Why use an online HTML formatter for cleaner, maintainable code?

Messy, inconsistently indented HTML is one of the most common sources of debugging friction in web development. When tags are collapsed onto a single line, attribute lists sprawl horizontally, or indentation levels drift between contributors, spotting a missing closing tag or a misplaced attribute becomes far harder than it should be. ToolJiffy's HTML Formatter solves this in a single click — paste your raw or minified markup and receive perfectly structured, readable HTML in seconds.

Powered by Prettier (MIT): The same battle-tested engine used by millions of developers and every major IDE extension — now running directly in your browser with zero configuration required.
Instant, offline formatting: All processing happens client-side via WebAssembly. Your HTML never touches a server, and the tool works without an internet connection once the page has loaded.
Handles minified input: Drop in a single-line minified HTML blob — the formatter parses the full AST and outputs properly nested, indented markup regardless of how compressed the original source is.
Consistent team output: Because the formatter is deterministic, two developers running the same HTML through it will always get the same result — eliminating whitespace-only diffs in pull requests.

Prettier's HTML parsing architecture

Under the hood, Prettier uses its own HTML parser — distinct from the browser's DOM parser — to build a concrete syntax tree (CST) that preserves comments, CDATA sections, and whitespace-sensitive inline elements like <span> and<code>. The printer then walks the CST and re-emits each node with correct indentation, respecting Prettier's "print width" concept: if an element fits on one line within 80 characters, it stays on one line; if it doesn't, Prettier breaks it into a multi-line block. This two-phase approach (parse then print) ensures the output is both human-readable and semantically identical to the input.

Void elements — <br>, <hr>, <img>,<input>, <meta>, and <link> — are always emitted without a closing tag, matching the HTML5 specification. Regular elements with no children retain their open and close tags as a pair, ensuring correct browser parsing behaviour across all rendering engines.

Client-side security for private HTML files

Because formatting runs entirely inside your browser, your HTML code is never uploaded to any server and never logged, stored, or shared. This makes the tool safe to use with proprietary templates, internal admin dashboards, or any markup containing sensitive structural information about your application.

ToolJiffy's formatter loads the Prettier WebAssembly bundle once from a CDN on your first visit, then caches it locally via the browser's standard caching mechanisms. Subsequent uses run fully offline — useful for developers working in restricted network environments or on flights.

Step-by-step guide to formatting HTML code

Paste or type your HTML into the input panel. You can paste anything from a single snippet to a full multi-page HTML document, including minified code from a build tool's output.
Click the Format button. Prettier parses the markup, rebuilds the syntax tree, and writes the formatted output to the right-hand panel — typically in under one second even for large files.
Copy or download the result. Use the Copy button to send the formatted HTML to your clipboard and paste it directly into your editor, or download it as an.html file for integration into your project.

When to format vs. when to minify HTML

Formatted (beautified) HTML is the right choice during development — it's easier to read, review in pull requests, and debug. Minified HTML removes all non-essential whitespace and is better suited for production builds where every byte of page weight matters. Most modern build pipelines (Vite, webpack, Parcel) automatically minify HTML at build time, so keeping your source files formatted adds no production overhead.

A good workflow is to keep formatted HTML in source control and run minification as a build step. ToolJiffy's formatter helps you maintain that readable source state — especially useful when receiving HTML from a third-party template or a low-code builder that outputs unreadable single-line markup.

Explore related developer utilities

Pair this tool with ToolJiffy's CSS Formatter to beautify your stylesheets with the same Prettier engine. For data payloads embedded in your HTML, theJSON Formatter pretty-prints and validates JSON. Need to compress your finished markup? Use the HTML Minifier to shrink your formatted source for production. Working with JavaScript in script tags? TheJavaScript Formatter applies Prettier's JS printer for the same consistent, readable output.

Frequently Asked Questions

How does the HTML formatter handle nested tags and indentation?
The formatter uses Prettier's HTML printer, which walks the full parse tree and re-indents every nested element with a consistent two-space indent by default. Each child element is placed on its own line, and deeply nested structures are indented proportionally, making the hierarchy immediately readable.
Are self-closing tags preserved when formatting HTML?
Yes. Prettier distinguishes between void elements like <br>, <img>, and <input> — which are always rendered as self-closing — and regular elements. Non-void elements with no children are kept as open/close pairs, so your semantics stay intact and browsers parse the output correctly.
Can I change the indent size or tab width?
The current tool runs with Prettier's default tab width of 2 spaces, which aligns with the most widely adopted HTML style guides. Future updates plan to expose a tab-width selector so you can choose 2 or 4 spaces to match your project's existing conventions.
How does Prettier format long attribute lists on HTML elements?
When an element's opening tag exceeds the print-width threshold (80 characters by default), Prettier breaks each attribute onto its own indented line and places the closing > on a new line. This keeps long attribute lists scannable without horizontal scrolling.
Can I paste minified HTML and get it fully formatted?
Absolutely. Minified HTML — including single-line documents with collapsed whitespace — is fully supported. Prettier rebuilds the AST from the minified source and outputs properly indented, readable HTML regardless of how compressed the input is.
Which version of Prettier is used by the HTML formatter?
The tool bundles Prettier 3.x (MIT-licensed), which ships with an improved HTML parser that handles template literals and whitespace sensitivity more accurately than version 2. The exact version is pinned in the project's package.json to ensure reproducible formatting output.
Does the formatter support HTML flavors like Vue templates or Jinja?
The formatter targets standard HTML5. Prettier does include partial support for Vue single-file component templates when the parser is set to "vue", but the current tool focuses on plain HTML. JSX, Jinja, and Nunjucks are not supported in this tool's current configuration.
How fast is the in-browser HTML formatter for large files?
Prettier runs entirely in your browser via WebAssembly, so formatting is typically instantaneous for files under 500 KB. Even large HTML documents with thousands of lines complete in under one second on a modern device. No network round-trip means zero latency from server calls.